1. Field of the Invention
The present invention is directed to an actuator locking mechanism of an information recording apparatus, and more particularly to a locking mechanism and a locking method for securing an actuator against an impact force applied from the outside by using an inertia member to be operated by the impact force.
2. Description of Related Art
In the case of an information recording apparatus such as a magnetic disk drive, a read/write transducer is provided for an actuator and the actuator is driven so that the transducer scans a recording medium. An actuator locking mechanism is used so that the transducer is moved to the outside of the recording region of the recording medium, that is, the stop position of the actuator when reading or writing is not performed. The actuator locking mechanism prevents the transducer from being moved into the recording region even if an impact force is applied to the magnetic disk drive from outside the unit while the actuator is resting at the stop position.
The fixed-magnet-type locking mechanism disclosed in Japanese Patent Unexamined Publication No. 151737/1993 is one example of the actuator locking mechanisms found in the art. The fixed-magnet-type locking mechanism is characterized by a simple structure which is easily decreased in size because the actuator is secured by attracting a part of the actuator resting at the stop position with a permanent magnet secured to the base of a magnetic disk unit. However, because the increase of a magnetic attraction force is limited, the actuator cannot be secured to the base against a large impact force applied to the actuator since magnetic attraction is disabled. Particularly, the requests for downsizing and portability of personal computers having a magnetic disk drive also require further downsizing of the magnetic disk drive, thereby limiting the increase of a magnet size in order to improve the securing force of the locking mechanism. The magnitude of an impact force applied to the magnetic disk drive in the personal computer is increased as the units become more portable, and accelerate the problem that the actuator cannot completely be secured at its stop position.
The solenoid-type locking mechanism provided with a solenoid and a mechanical latching mechanism is another locking mechanism disclosed in Japanese Patent Unexamined Publication No. 151737/1993. The solenoid-type locking mechanism makes it possible to obtain a large actuator securing force. However, because the structure is complicated and increased in size compared to the magnet type, it is not very suitable as the actuator locking mechanism of the magnetic disk drive for which downsizing and portability are requested.
As described above, a conventional actuator locking mechanism has a problem that it cannot show a large securing force as it is decreased in size. Accordingly, it can be seen that there is a need to provide an actuator locking mechanism having a simple structure like the magnet type and a securing force not limited by the attraction force of a magnet.